A new study sheds light on how children are affected by their parenting, and their genetic inheritance.

In a recently published study, researchers looked at a gene area called 5-HTTLPR, the so-called depression gene, which has both short and long versions; some studies have associated this area with higher risk of depression in stressful environments.

The researchers, a team from the University of Denver, Rutgers University, the University of Colorado-Boulder, and the University Medical Center Groningen in the Netherlands, were investigating their hypothesis that children and adolescents carrying short alleles of 5-HTTLPR would be more influenced by parenting.

They investigated this potential gene-environment interaction (GxE) in three independent studies of children and adolescents aged 9 through 15.

The first study included 307 children and adolescents recruited from public schools. Each child provided a DNA sample by buccal swab. A parent completed the Alabama Parenting Questionnaire, a measure of positive parenting, and the children completed the positive affect subscale from the Positive Affect and Negative Affect Scale for Children.

The second study had 197 children and adolescents recruited from public schools, who also provided a DNA sample. They then completed the Positive Affect and Negative Affect Scale for Children. Parenting behaviors were ascertained during videotaped observations of parent-child interactions in the laboratory. Behaviors were coded on a 1 to 5 scale by a trained team of reliable coders, the researchers note.

The third study consisted of 1,370 participants in the Dutch study Tracking Adolescents’ Individual Lives Survey (TRAILS). Parenting was assessed by the 18-item Emotional Warmth scale of the EMBU (a Swedish acronym for My Memories of Upbringing) for children (EMBU-C), and by the Behavioral Activation System Drive scale of the Behavioral Inhibition System/Behavioral Activation System scales, selected for its high correlation with positive affect as assessed by the Positive Affect and Negative Affect Scale. DNA was extracted from buccal swabs or blood samples from the children.

“Results from all three studies showed that youth homozygous for the functional short allele of 5-HTTLPR were more responsive to parenting as environmental context in a ‘for better and worse’ manner,” said Benjamin Harkin, Ph.D., an associate professor of clinical child and developmental cognitive neuroscience psychology at the University of Denver.

Hankin used the analogy that some children are like orchids, while others are like weeds. The weeds flourish anywhere. But the orchids need an optimal environment to flourish.

“If the environment is bad, these children have worse outcomes, but if it is good, they have much better outcomes,” Hankin said. “What this shows is that for these children, even in the age of genetics, parenting really, really matters. It isn’t nature or nurture, it’s both.”

Hankin says there is no need to get children genotyped, but notes that parents should pay attention to children who are more irritable.

“With these kids, your input has a greater impact,” he said. “As your child grows up, the challenges are going to change, but you can put your kid on a trajectory for more adaptive, positive mental health.”